Controlling atmospheric pollution is a concern of increasing importance as the levels of various atmospheric pollutants continue to increase. One primary pollutant of concern is ozone. Various components in the atmosphere can lead to the production of ozone and these compounds include those produced by internal combustion engines. Volatile organic compounds and oxides of nitrogen released into the atmosphere are two primary precursors that lead to formation of ozone in the air via photocatalysis. Most pollution control measures are directed toward removing such ozone precursors at the emission sources.
Recently, a new technology has emerged for treatment of ozone at the ground level utilizing vehicle heat exchangers. Examples of this technology can be found in U.S. Pat. Nos. 6,214,303; 6,212,882; 6,200,542; 6,190,627, and 5,204,302. These patents disclose methods for treating atmospheric pollutants by contacting the atmosphere with a catalytic composition on the surface of a substrate. The difficulty with this current technology is that getting the catalytically active compounds to adhere to the substrate requires the use of complicated binders, adhesive layers, and complex surface treatments. These procedures generally involve immersing the entire heat exchanger in a series of coating slurries to obtain a catalytically active surface. The equipment for carrying out these procedures is large and there is the additional difficulty of treating the residue. Finally, treatment of vehicle heat exchangers by these methods can tend to lead to a reduction in the heat exchange efficiency of the heat exchanger, which is undesirable.
It would be advantageous to provide a method for application of catalytically active substances to a substrate that is simple, can be incorporated easily into existing production facilities, is a one-step process, and that can be utilized to apply catalytically active substances to a variety of substrates in addition to heat exchangers.